Follow-up on AsyncSequence and parity with Sequence based APIs

[xwu (Xiaodi Wu)]

@Philippe_Hausler

A number of these were omitted due to missing features of the language that had not yet been proposed.

@Philippe_Hausler

This means that the act should be rethrows according to the conformance of the type it is called upon. Furthermore collecting all values must also be in it of itself asynchronous.

extension AsyncSequence {
  public func collect() async rethrows -> [Element]
}

This all requires "rethrowing protocol conformances" pitched before, which hasn't yet been reviewed or re-pitched, yes? (I'd be very interested in seeing how the authors refine that pitch in light of the issues discussed in the first pitch thread.)